The present invention relates to engine knocking detecting means.
Conventionally, engine knocking detecting means include engine vibration sensors mounted on engines for sensing engine vibrations and producing engine vibration signals which are passed through appropriate filter circuits so that only the signals of frequency band corresponding to engine knocking vibrations are passed to detecting circuits. Usually, the detecting circuits include integrating circuits for integrating the signals from the filter circuits to produce signals representing intensities of the knocking. The conventional arrangements can perform accurate and precise detections of the intensities of the engine knocking when the engine knocking is produced occasionally or intermittently. However, for repetitive engine knocking, a succeeding signal is produced while a preceding signal is being integrated so that the signals may be superposed possibly causing a measurement error.
In Japanese patent application No. 54-112429 filed on Sept. 4, 1979 and disclosed for public inspection on Apr. 13, 1981 under the disclosure number 56-38562, there is disclosed an engine knocking detector in which the engine vibration signals representing engine knocking are converted into pulse signals which are counted to detect the engine knocking. The proposed engine knocking detector is however inconvenient because it simply counts the number of vibration signals but cannot discriminate a weak engine knocking from a strong one. Since the engine knocking detectors are used for controlling the engine operating conditions such as ignition timing or air-fuel ratio of the intake mixture, such inconveniencies disturb precise control of engine.